Minimum Mass of a Pressure Vessel Formula

Equation for calculate minimum mass of a pressure vessel is,

$$M=\frac{3}{2}\times \mathrm{P•V}\times \frac{\mathrm{\rho }}{\mathrm{\sigma }}$$

where,
M = Mass
P = Pressure difference from ambient (the gauge pressure)
V = Volume
ρ = Density of the pressure vessel material
σ = Maximum working stress that material can tolerate